The race to be the world’s biggest passenger jet maker has taken a new turn as Ryanair, one of Boeing’s biggest customers, hints at switching to Airbus, the US group’s European rival.

The Irish no-frills carrier, which said it was looking at ordering up to 300 jets, said it would be foolish to disregard Airbus as the manufacturer weighs plans to upgrade its best-selling A320 aircraft with new engines, a move Airbus said could cut fuel bills by as much as 15 per cent.

No formal talks are under way, and the prospect of such will seem distant to some, given the chilly relations since Ryanair abandoned talks with Airbus for a lucrative aircraft order it eventually placed with Boeing nearly five years ago.